The Botany of the Antarctic Voyage/Part I/Stylidieae
XVI. STYLIDIEÆ, Br.
1. FORSTERA, L.
Flores monoici v. dioici. Calyx basi bibracteolatus, limbo 3-6-partito, segmentis erectis. Corolla tubuloso-campanulata, tubo brevi v. elongato, limbo 4–9-partito, segmentis inæqualibus, æstivatione imbricatis, 1–2 ext. majoribus, patulis concavis, fauce nuda v. glanduloso-incrassata. Glandulæ epigynæ 2, oppositæ, semilunares, staminibus alternæ. Antheræ ad apicem columnar oppositæ, divaricatæ, reniformes, spurie biloculares, rima transversali dehiscentes, valvula superiore majore fornicata. Pollen 3-5-angulatum. Stylus iutra columnam occlusus. Stigma (v. apex styli) minimum, 2-lobum (an 4-lobum?), ramis floribus fertilibus porrectis, superne villosis v. subplumosis. Ovarium obovatum, carnosum, uniloculare, rarius biloculare, multiovulatum, ovulis columnæ centrali funiculis brevibus adnexis, ascendentibus. Capsula ovalis, unilocularis.—Herbæ parvæ, perennes, glabræ, coriaceo-carnosæ, antarcticæ seu montibus altissmus Novæ Zelandiæ provenientes. Folia imbricata. Flores in summos ramos sessiles, v. pedunculos elongates solitarii v. bini.—Endl.
§ Helophyllum, Hook. fil.; floribus sessilibus solitariis, calycis limbo 5-6-partilo, lobis æqualibus, foliorum apicibus nodoso-incrassatis.
1. Forstera clavigera, Hook. fil.; densissime et compacte cæpitosa, caulibus erectis parce ramosis, foliis arete imbricatis semiteretibus apicibus nodoso-incrassatis, floribus terminalibus sessilibus solitariis. (Tab. XXVIII.)
Hab. Lord Auckland's group and Campbell's Island; on the mountains in turfy and boggy places, very common.
Caules erecti, stricti, parce ramosi, densissime compacti, cæspites firmos fragiles formantes, per totam longitudinem foliosi, hinc illinc axillis foliorum radices fibrosas emittentes, fibris validis elongatis fuscis horizontaliter patentibus carnosis simpliciusculis, et deorsum in radices subsimiles gradatim attenuatæ, 1½–2 pollicares, una cum foliis diametro ¼ pollicis. Folia undique inserta, creberrime imbricata, numerosissima, stricta, erecto-patentia, linearia, obtusa, glaberriina, basi dilatata subvaginantia, marginibus tenuiter membranacea, medio subcontracta, dorso teretia, antice anguste plana vel canaliculata, ad apices globoso-incrassata, coriacea, crassa, dura, viridia, nirida, 2½–3 lin. longa; adulta inferne turgida, subampullacea, fusco-brunnea, suberosa, laxius imbricata. Flores ad apices ramulorum omnino sessiles, inter folia occlusi, limbo corollæ solummodo exserto, verosimiliter monoici, v. potius hermaphroditi. Calycis tubus brevis, turbinatus, v. floribus masculis obconicus, basi bibracteolatus; limbus 5–6-partitus, lobis linearibus obtusis erectis carnosis semiteretibus medio uninerviis, dorso infra apices pilosis, tubo corollæ æquilongis; bracteolæ oppositæ, segmentis calycinis simillimæ, basi remotæ. Corolla campanulata, albida; tubus latus, brevis, teres; limbus sub-bilabiatus, nempe inæqualiter 5-9-partitus, segmento unico v. duobus cæteris majoribus, rarius 4-partitus, segmento unico maximo 2-nervi, omnibus obovatis obtusis concavis planis v. ad faucem biglandulosis sinubusque incrassatis. Glandulæ epigynæ 2, oppositæ, semilunares, columnæ basin fere cingentes, crassæ et carnosæ, virides, antheris alternæ. Columna valida, erecta, ante anthesin protrusa, recta v. paululum inclinata, teres, superne incrassata. Antheræ 2, ad apicem columnæ sessiles, transversæ, majusculæ, reniformes, v. potius hypocrepiformes, divaricatæ, 1-loculares, connective carnoso in loculum porrecto costam elevatam formante, hinc spurie biloculares, linea curvata homotropa horizontaliter dehiscentes, valvis subcarnosis cellulosis purpureis inæqualibus, superiore majore fornicato sub-erecto post anthesin revoluto, inferiore horizontaliter porrecto marginibus lateralibus revolutis. Pollen opacum, 3-4-angulatum, flavo-viride, minutissime granulatum, angulis globoso-incrassatis, margine hyalino cinctum. Stylus floribus abortivis intra antheras occlusus, parvus, angustus, inconspicuus, convexus, v. brevissime bilobus; floribus fertilibus bilobus, lobis porrectis divaricatis antheris alternis uncinatis carnosis sursum glanduloso-plumosis. Ovarium flore masculo angulatum, pedicellum breve crassum simulans; flore fertili late obovatum, v. turbinatum, teres, carnosum, 1- rarius 2-loculare, ∞ ovulatum; ovulis parvis ascendentibus. Capsula immatura coriaceo-caraosa, 1-locularis. Semina semi-matura 6-8, obovata, ascendentia; testa membranacea, pallide brunnea; albumine carnoso. Embryo non visa.
Though abundant upon the hills of Lord Auckland and Campbell's Islands, this plant has not hitherto been brought from any part of New Zealand, neither from the mountains of the Northern Island, whence Mr. Bidwill and Mr. Colenso have sent home several of the more common Antarctic species, nor in the southern parts of that group, so well explored by Forster and Menzies. In general habit and appearance it bears a greater similarity to the Phyllachne uliginosa, Forst., than to its New Zealand congener, Forstera sedoides, L., although in the more essential characters it is much more nearly allied to the latter, the leaves being entire, the calycine segments equal and regular, and the epigynous glands much developed. In other respects, and especially in the mode of growth and form of the leaves, the present plant is so dissimilar from either, that I have ventured to place it under a separate sectional name, adopted in allusion to the incrassated apices of the leaves.
There are several points in the structure of the three plants above alluded to which seem to require some consideration; and having the opportunity of examining the flowers of all the species, I shall here offer a few remarks upon them, premising that, except in the case of F. clavigera, the specimens at my disposal were too few to allow of the full verification of the observations.
Linnæus first supposed Phyllachne to be monœcious (Suppl. Plant, p. 62), and Swartz (Schrader, Journ. fur Botanik, vol. i. p. 273, translated in Kœnig's Annals, vol. i. p. 286) follows Forster (Charact. Gen. t. 58) in supposing both this and F. sedifolia to be dioœcious. If, as I suspect, the only truly fertile flowers of F. clavigera are such as bear the uncinate plumose styles, that plant is certainly monœcious. Out of very many flowers examined, I only found such stigmata in two, both of which had abortive anthers, and they were moreover furnished with the only capsules in which I saw the immature seeds brown, and apparently fertile. Though there is a marked difference in the development of the apex of the style in the abortive flowers of this plant, it never, that I have seen, approaches the form it bears in the fertile flowers; at all other times it is exceedingly minute and probably variable in the lobes. Of the P. uliginosa I examined six flowers, only one of which contained perfect stigmata; in it the style branched into two capitate arms, pubescent externally, and in all respects analogous to the stigmata of the former plant; the ovary was however in so very young a state, that I could not detect any concomitant character in the ovules; the anthers were decidedly abortive. In F. sedifolia, L., I have seen no other stigmata than two small uncinate fleshy bodies, concealed between the two upper valves of the anthers, parallel with them, and alternating with two small glands ? at the back of these organs. In form and situation they answer to the plumose stigmas of the two former, but they are smooth throughout. In another flower I find the apex of the style to be depressed and to appear minutely 4-lobed, with the lobes unequal and rounded: in both these cases the anthers were full of pollen, and the ovules in a rudimentary state. In Swartz's description of this plant he notices a crest of projecting hairs, arising from a fleshy septum, obscurely lobed under the microscope, which connects the two anthers and separates the two lobes of the true apex of the style or stigmas. Swartz distinctly alludes to the two small glands or stigmata as being protected by the upper valves of the anthers, and they are hence probably analogous to two of the four lobes into which, in the flower I examined, the apex of the style appeared to be divided. Swartz's supposition, that the septum and crista of fine hairs form a connectivum between the anthers, separating the stigmata, appears to me to indicate a most anomalous condition of those parts; and as it is, from its position and structure, analogous to the arms of the style and stigmata in the two former species, I conclude that that author examined fertile flowers of F. sedifolia. It is still more remarkable that so acute and very accurate an observer should have been unable to detect the glands at the base of the column, which in both my specimens are exceedingly large, and project upwards like two horns from the top of the ovarium for half the length and upwards of the tube of the corolla, and whose apices in the young state of the flower lie between the anthers. It is possible that they may be obscurely developed in fertile flowers of this species, which however is not the case in those of F. clavigera or of Phyllachne uliginosa.
In F. clavigera there are apparently two very different states of the corolla: in many of my specimens of this plant that organ is divided into 5–7 lobes, all of them concave and even, of the same thickness throughout; more rarely they are 4 or 9; but in other corollas taken from the same specimens the divisions are undulated, with the borders of the sinuses much thickened, and each of them furnished at the throat with two linear, elevated, divaricating ridges or glands, which branch off from the middle nerve in the upper part of the tube, and are abruptly clavate at the extremity, near the margin of the segment, with whose thickened margins they sometimes unite. In some respects they resemble the nectaries of Ranunculus pinguis (Tab. I.), being only occasionally present; they however contain no secretion. Though I could trace no connection between this, the common form of the corolla, and the fertile or abortive state of the ovarium, I may remark, that where the segments are smooth and even, the apex of the style is hardly prominent or visible between the anthers, and also that in the most divided corollas the segments were most undulated and thickened; in F. sedifolia they are also very distinct, though nowhere described that I am aware of; and they are also evident, but not so fully developed, in the few flowers of Phyllachne which I have examined. I have also described the corolla as somewhat two-lipped, a character not very evident in all instances, and depending upon the inequality and comparative size of the segments; one or two are almost invariably larger than the rest, and external in æstivation; when there are two large lobes they are placed near one another; and when the corolla has more than five segments, these two are subdivided into four by short sinuses; where only four segments exist, it is caused by the union of two of the small lobes.
All the species have the anthers spuriously 2–celled, by means of a thick fleshy ridge which runs at the base of the anther, between the valves, and projects half-way across the cavity. After the dehiscence of these organs, they together form a cross placed horizontally on the top of the column, from their unsymmetrical contraction; of these, the lower one on each side projects horizontally and forms a right angle with the axis of the column, its two lower lobes approximating below; the upper becomes erect, and its upper margin being revolute, meets that of the opposite anther; this appearance is represented at fig. 10. The ovary, which is generally 1-celled, I have rarely found divided into two cells by a more or less thickened septum. Two bundles of vessels, one from each of the arms of the style, meet in the column and traverse its length; at the summit of the ovarium they sometimes again divide, and as separate cords enter its cavity, meeting again in the central column which bears the placentæ.
The last circumstance to which I shall here allude concerns the inflorescence of these species of Stylidiæ. In one of Mr. Bidwill's specimens of F. sedifolia from the mountain of Tongariro, in the Northern Island of New Zealand, the peduncle is 2-flowered, and the position of the bracts on the pedicels, and at the base of the ovaria, shows their true situation and the nature of the inflorescence to be the same in Forstera as in many Stylidia. This two-flowered specimen has six bracts, two of which are placed at the forking of the peduncle, one situated upon and belonging to each of the pedicels; but the other four form two pairs, each pair placed immediately at the base of the ovarium. In the solitary and sessile-flowered species it is sometimes difficult to distinguish the bracts from the upper leaves; in F. clavigera however they are sufficiently distinct, but never more than two, nor in P. uliginosa are there probably more, though they gradually pass into the ordinary forms of the leaf. In the latter plant some foliaceous expansions, which are generally considered as segments of the calyx, are often placed upon the germen; I have not remarked how they are disposed upon distinctly fertile ovaria of this species; where however that organ is imperfectly developed, it may be readily understood how a little irregularity in the insertion either of the calycine lobes or bracts might lead to the one being mistaken for the other.
Plate XXVIII. Fig. 1, branch of F. clavigera with an expanded plicate corolla, and the arms of the style developed; figs. 2 and 3, cauline leaves from the same; fig. 4, flower with the segments of the corolla even and plane; fig. 5, a portion of a corolla from fig. 1; fig. 6, ovarium and epigynous glands; fig. 7, column with perfect anthers; fig. 8, longitudinal section of the same; fig. 9, pollen from the same; fig. 10, anthers after the pollen has escaped; fig. 11, column with stigmata and imperfect anthers; fig. 12, transverse section of 1-celled ovarium ; fig. 13, longitudinal section of 2-celled do.; fig. 14, immature seeds:—all magnified.